1. Field of the Invention
This invention lies in the field of automatic and semi-automatic forming apparatus and in the field of methods of using such apparatus to carry out a series of forming operations to provide stabilizer bars or sway bars in predetermined shapes as are determined by the manufacture of automobiles, trucks and trailers and includes methods and apparatus for stiffening and hardening the formed articles to produce permanent strengthened stabilizer bar products.
This invention relates more specifically to tubular vehicle stabilizer bars having end portions of strengthened constructions which have an opening adapting the ends of the bar to be bolted to the frame of the vehicle. The end portions are strengthened by utilizing swaging techniques or tubular inserts.
2. Description of the Prior Art
Urschel, U.S. Pat. No. 2,318,344, shows an apparatus for automatically forming vehicle stabilizer bars. The device comprises a plurality of cylinders mounted on a support which are sequentially actuated to bend the initially straight, heated bar into the desired configuration. The Urschel apparatus also includes quenching means to spray a cooling liquid onto the bar after it has been bent so as to hold the bar in its final shape as it cools.
Brogren, U.S. Pat. No. 2,565,717, discloses a tube bending apparatus wherein the bending mechanism is mounted onto a board-like support structure.
Sassak, U.S. Pat. No. 3,362,209 and Foster et al, U.S. Pat. No. 4,131,003, show fully automatic (Sassak) or semi-automatic (Foster et al) control systems for bending apparatus.
Brown, U.S. Pat. No. 2,955,639, discloses a simple device for bending pipe in which a shoe is held against movement of the plunger to provide a single, rather than a compound bend.
It has long been recognized that tubular stabilizers for vehicles may require special heat treatments or separate cold working treatments in order to strengthen the ends of the stabilizer bars and examples of strengthened pipe ends are found in the prior art in which both cold working and hot working may be needed. For example, Tirone, U.S. Pat. No. 3,354,689, shows the piercing of bar stock or rod stock, shows drilling or piercing at the end to provide a beveled inset in the punched area at the end of the stock.
Another example for providing an eye at the end of a blank is found in the patent to Stout, U.S. No. 3,967,487, in which a special forming of the end of a leaf spring blank is carried out in a hot forging operation after which there is a hole punching operation to form eyes or openings at each end of the blank.
Still another example of a process for forging a tubular metal blank into a flattened shape in which the temperature condition for working is from 550.degree. to 1250.degree. C. is shown in the patent to Shinosaki, et al, U.S. No. 4,527,411, but the flattening in this patent is different from that of the present invention.
Further, it is known in the prior art that the steps of drop forging followed by trimming to cut away flash metal which is produced during forging and then followed by swaging to produce a predetermined increase in thickness is those parts subject to greater stress has been utilized in the forging of hammer heads as taught by Vlchek, U.S. Pat. No. 1,838,470.
Mogford et al in U.S. Pat. No. 1,823,158, shows the method of strengthening the ends of a hollow axle by the steps of forging and upsetting the end portions of the tubular pre-form used in making the axle, then inserting a plug after the metal has been upset and thereafter forging the end to provide a uniform joining of the insert with the outer tubular portion to facilitate the formation of a strengthened inner portion adjacent the apertured end of the axle.
In U.S. Pat. Nos. 4,372,576, Inoue, 4,378,122 and 4,429,899, Ohno et al, although stabilizer bars are shown which are formed of curved welded metal pipe, in each of these patents the end portion of the stabilizer bar is the same. In Inoue, U.S. Pat. No. 4,372,576, the seam of the welded pipe is located in a critical position which is determined as a result of the relationship between the thickness of the pipe to the outer diameter of the pipe and the stabilizer of this patent is formed by cold working. In Ohno et al, U.S. Pat. No. 4,378,122 there is a change in the diameter of the interior of the hollow pipe. In Ohno et al, U.S. Pat. No. 4,429,899 there is a separate portion section which is formed near the end of the pipe which is of much smaller diameter and a plurality of curved sections are provided within the pipe to render the manufacturing operation complex. It requires cold forming to provide this complex end shape.
In U.S. Patent to Falk, Pat. No. 3,886,780, a two piece fitting is provided in which an aperture in one of the fittings is shown and which is for the purpose of inserting a tool to disassemble the front element from the back element of the two piece fitting. Insofar as application is aware, there is no other patent which teaches an aperture in a compressed end of a pipe for an eye opening such as forms a part of the present invention.
Another example of a stabilizer bar device which includes specially formed end joints is found in Anderson, U.S. Pat. No. 4,138,141, who discloses separate permanent end joints which are press fitted into the ends of a central tubular member.